A bionic layout optimization method for a twin-torpedo underwater vehicle group

Abstract

The application discloses a bionic layout optimization method for a double-torpedo underwater vehicle group, and the method comprises the following steps: dividing the underwater vehicle according to the fluid flow direction, and constructing a partition linear equation; setting a ring-shaped pit structure on the head surface of the underwater vehicle, and connecting the underwater vehicles in series to form a double-torpedo underwater vehicle group; performing simulation analysis on the underwater vehicle group, and calculating the drag reduction rate of the underwater vehicle group; and determining the underwater vehicle spacing and the bionic shark rib ring-shaped pit structure parameters according to the drag reduction rate, the underwater vehicle spacing range and the bionic shark rib ring-shaped pit structure parameter range. The application combines the surface drag reduction and the arrangement layout drag reduction, and the series connection structure reduces the pressure difference resistance of the latter vehicle and the flow rate of the fluid flowing through the head of the latter vehicle, and compared with the high flow rate state, the ring-shaped pit structure on the head has a stronger secondary vortex and rolling bearing effect on the low-speed flow passing through the tail, thereby further reducing the viscous resistance and realizing the superposition of the drag reduction effect.

Description

TECHNICAL FIELD

[0001] The present application relates to a composite drag reduction method, in particular to a bionic layout optimization method of a double torpedo underwater vehicle group. BACKGROUND

[0002] Underwater robots have become a necessary part of exploring facilities in the ocean, and autonomous underwater vehicles (AUVs) have been used in many fields such as mineral exploitation, underwater exploration, and geographic mapping, which can be remotely controlled without human operation, greatly reducing the cost while ensuring safety. On the basis of mature manufacturing technology, increasing the efficiency of underwater vehicle fuel and reducing the resistance during travel has become the top priority of underwater vehicle research. Compared with time-consuming and expensive experiments, CFD computational fluid dynamics has developed continuously, and the results of numerical simulation have been verified by experiments, with high accuracy. However, research often focuses on single vehicles, and the flow and interaction of two or more vehicles in a group are more complex. SUMMARY

[0003] The present application aims to provide a bionic layout optimization method of a double torpedo underwater vehicle group that combines composite surface design and layout arrangement to achieve drag reduction effect superposition.

[0004] Technical scheme: The bionic layout optimization method of the double torpedo underwater vehicle group comprises the following steps:

[0005] (1) The torpedo underwater vehicle is divided into zones according to the direction of fluid flow, including a head, a middle, and a tail connected in sequence;

[0006] (2) Linear equations of the head, middle, and tail are constructed to obtain a torpedo underwater vehicle with a streamline body shape;

[0007] (3) A bionic shark rib ring-shaped pit structure is arranged on the surface of the head of the torpedo underwater vehicle, and the torpedo underwater vehicles are connected in series to form a double torpedo underwater vehicle group;

[0008] (4) The double torpedo underwater vehicle group is simulated and analyzed to calculate the drag reduction rate of the double torpedo underwater vehicle group;

[0009] (5) The underwater vehicle spacing and bionic shark rib ring-shaped pit structure parameters are determined according to the drag reduction rate of the double torpedo underwater vehicle group, the underwater vehicle spacing range, and the bionic shark rib ring-shaped pit structure parameter range.

[0010] Further, step (2) comprises the following steps:

[0011] (21) take the head tip of the first underwater vehicle as point o, set the horizontal axial direction as x-axis, set the radial direction perpendicular to the axial direction as y-axis, set the z-axis perpendicular to the oxy plane and taking the head tip as the starting point, thus establishing a three-dimensional rectangular coordinate system, and the oxy plane is taken as the main two-dimensional observation coordinate reference system;

[0012] (22) according to the diameter D of the torpedo underwater vehicle, determine the linear equations of the head, middle and tail.

[0013] Further, the linear equation of the head is:

[0014]

[0015] In the formula, Y represents the radial length, x represents the axial distance in the two-dimensional plane of the underwater vehicle, D represents the diameter of the underwater vehicle, and a is the length of the head of the underwater vehicle;

[0016] The linear equation of the middle is:

[0017]

[0018] In the formula, Y represents the radial length;

[0019] The linear equation of the tail is:

[0020]

[0021] In the formula, Y represents the radial length, and a, b and c are the lengths of the head, middle and tail of the underwater vehicle, respectively.

[0022] Further, in step (3), the bionic shark rib ring-shaped pit structure is a rectangular pit, the depth h of the rectangular pit is 0.5-1mm, and the bottom surface length L a is 3-4mm.

[0023] Further, in step (3), the bionic shark rib ring-shaped pit structure is arranged on the surface of the head of the underwater vehicle according to the five equal division points of the head curve.

[0024] Further, in step (3), the distance L D between the two underwater vehicles in the double-torpedo underwater vehicle group is 90-120mm.

[0025] Preferably, in step (5), when the drag reduction rate does not meet the requirements, the distance L D between the underwater vehicles is adjusted with higher priority than the depth h of the bionic structure, and the depth h of the bionic structure is adjusted with higher priority than the bottom surface length L a .

[0026] Beneficial effects: compared with the prior art, the application has the following advantages: 1, the application combines the drag reduction of non-smooth surface with the arrangement and layout of drag reduction, and the series structure greatly reduces the pressure difference resistance of the latter vehicle and the flow rate of the fluid flowing through the head of the latter vehicle, and compared with the high flow rate state, the annular pit structure of the head has a stronger secondary vortex and rolling bearing effect on the low-speed flow through the tail, further reducing the viscous resistance, realizing the superposition of the drag reduction effect; 2, the series vehicle realizes the remarkable drag reduction effect at the lowest cost, has the characteristics of high efficiency and convenience, and is easy to operate; 3, the bionic shark fin rib annular pit structure in the application is different from the conventional two-dimensional elliptical or V-shaped groove, and the rectangular groove is used on the three-dimensional curved surface, which has no effect on the whole vehicle and no pollution to the environment. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a structure schematic diagram of the underwater vehicle of the embodiment Myring type;

[0028] Figure 2 It is a real object diagram of the shark scale structure under the scanning electron microscope;

[0029] Figure 3 It is a whole model schematic diagram of the underwater vehicle head attached with the bionic pit structure in the embodiment;

[0030] Figure 4 It is a wall friction coefficient comparison curve diagram of the underwater vehicle head attached with the bionic pit structure in the embodiment and the original model;

[0031] Figure 5 It is a whole structure schematic diagram of the underwater vehicle group in series in the embodiment;

[0032] Figure 6 It is a wall pressure coefficient change curve diagram of the underwater vehicle group in series in the embodiment;

[0033] Figure 7 It is a whole structure schematic diagram of the underwater vehicle group after comprehensive optimization in the embodiment;

[0034] Figure 8 It is a head local friction coefficient change curve diagram of the underwater vehicle group after comprehensive optimization in the embodiment relative to the non-smooth surface and the original model. DETAILED DESCRIPTION

[0035] The application will be further described below in combination with the drawings.

[0036] The bionic layout optimization method of the double-torpedo underwater vehicle group described in the application comprises the following steps:

[0037] (1) the torpedo underwater vehicle is divided into zones according to the fluid flow direction, including the head, the middle part and the tail connected in sequence;

[0038] (2) Construct linear equations for the head, middle and tail sections to obtain a torpedo underwater vehicle with a streamlined body shape;

[0039] (3) A biomimetic shark rib ring-shaped recess structure is set on the head surface of the torpedo underwater vehicle, and the torpedo underwater vehicles are connected in series to form a double torpedo underwater vehicle group.

[0040] (4) Simulate and analyze the double torpedo underwater vehicle group and calculate the drag reduction rate of the double torpedo underwater vehicle group.

[0041] (5) Based on the drag reduction rate of the dual torpedo underwater vehicle group, the range of underwater vehicle spacing, and the range of parameters of the biomimetic shark rib annular recess structure, determine the underwater vehicle spacing and the parameters of the biomimetic shark rib annular recess structure; when the drag reduction rate meets the requirements, the optimization is complete; when the requirements are not met, first adjust the distance L between the vehicles. D The relative effect of the structure on the overall resistance is greatest, followed by adjusting the depth h of the biomimetic structure, and finally adjusting the length L of the bottom surface. a Continue until the requirements are met.

[0042] like Figure 1 The Myring-type hull model shown with optimal parameters is divided into a bow (1), midsection (2), and stern (3), with corresponding lengths of a, b, and c, respectively. The diameter of the underwater vehicle is D. A three-dimensional Cartesian coordinate system, oxyz, is established with the tip of the underwater vehicle's bow as the origin o, the direction of the incoming flow (axial direction) as the x-axis, the radial direction as the y-axis, and the direction perpendicular to the oxy plane as the z-axis. oxy is used as the primary visible two-dimensional plane.

[0043] The following parameters are determined: vehicle diameter D = 50 mm, vehicle overall length 450 mm, forebody length a = 53.75 mm, midbody length b = 288.75 mm, and aftbody length c = 107.5 mm.

[0044] Based on the above parameters, determine the linear equations for each part of the anterior, middle, and posterior body.

[0045] Head 1, coordinate range and linear equation are as follows:

[0046] 0 < x1 < 53.75 mm

[0047]

[0048] Part 2, the coordinate range and linear equation are as follows:

[0049] 53.75 < x2 < 342.5 mm

[0050] Y = 25 (5) Tail 3, coordinate range and linear equation are respectively:

[0051] 342.5 < x3 < 450 mm

[0052] Y = 25 - 0.0031(x - 342.5) 2 +0.0000087524(x-342.5) 3 (6)

[0053] The biomimetic structure is inspired by sharks, such as Figure 2 As shown, its surface structure gives it good drag reduction capabilities when swimming, making the movement more efficient. In this embodiment, it is simplified into a rectangular pit structure.

[0054] like Figure 3 As shown, the annular rectangular recess structure is evenly distributed on the surface of the vehicle's nose at five equal points along the curve, with a depth h = 1 mm and a bottom length L. a With a diameter of 3 mm, a numerical simulation was conducted on an underwater vehicle with a single attached biomimetic drag reduction element under the conditions of flow velocity U = 3.05 m / s and no slip boundary conditions. Figure 4 The comparison of the wall friction coefficients of an underwater vehicle with an annular recess structure and an underwater vehicle with a smooth surface is shown. The non-smooth rectangular recess causes fluctuations in viscous drag, making its level lower than that of the smooth surface, which proves the drag reduction capability of the annular recess.

[0055] like Figure 5 As shown, two smooth underwater vehicles are connected in series. The first and second underwater vehicles are designated as underwater vehicle 1 and underwater vehicle 2, respectively, with a distance L between them. D =90mm, numerical simulations were performed under the same conditions. Figure 6 The diagram shows the change in pressure coefficient of the tandem underwater vehicle group. It is clear that the pressure at the head of the No. 2 underwater vehicle is lower, which significantly reduces the pressure difference between the head and tail of the No. 2 underwater vehicle, thereby reducing the overall drag of the underwater vehicle group.

[0056] like Figure 7 As shown, a numerical simulation was performed under the same conditions as described above, combining the series configuration with a non-smooth surface. Figure 8 The results show the friction curve changes of the optimized No. 2 underwater vehicle against a general non-smooth surface and the local wall of the nose of the original underwater vehicle. Compared with a general non-smooth surface, the series-connected annular pit structure has a better anti-adhesion effect. This means that the series arrangement further enhances the drag reduction performance of the non-smooth surface. The numerical simulation results are summarized in the table below. The numerical results show that the comprehensively optimized underwater vehicle group has a better drag reduction capability, achieving a superposition of drag reduction effects. Optimal drag reduction parameters were used in this embodiment.

[0057]

[0058] The application applies the bionic pit structure to the head of the underwater vehicle, forms a composite surface, significantly reduces the overall viscous resistance, connects the underwater vehicles with the bionic structure surface in series according to a certain interval, reduces the flow velocity, promotes the drag reduction ability of the bionic structure, combines the composite surface design and layout arrangement, reasonably uses the underwater interaction between the vehicles, realizes the superposition of the drag reduction effect, realizes the optimization design and layout of the underwater vehicle group at a low cost, reduces the resistance and energy consumption in the running process, and improves the overall efficiency.

Claims

1. A method for bionic layout optimization of a twin-torpedo underwater vehicle group, characterized in that, The method comprises the following steps: (1) dividing the torpedo underwater vehicle into zones according to the fluid flow direction, including a head, a middle part and a tail connected in sequence; (2) constructing linear equations of the head, the middle part and the tail to obtain a torpedo underwater vehicle with a streamline body shape; (3) arranging a bionic shark rib ring-shaped pit structure on the surface of the head of the torpedo underwater vehicle, and connecting the torpedo underwater vehicles in series to form a double torpedo underwater vehicle group; (4) performing simulation analysis on the double torpedo underwater vehicle group, and calculating the drag reduction rate of the double torpedo underwater vehicle group; (5) determining the underwater vehicle spacing and the bionic shark rib ring-shaped pit structure parameters according to the drag reduction rate of the double torpedo underwater vehicle group, the underwater vehicle spacing range and the bionic shark rib ring-shaped pit structure parameter range.

2. The method of bionic layout optimization of the dual-torpedo underwater vehicle group according to claim 1, characterized in that, Step (2) comprises the following steps: (21) Taking the tip of the first underwater vehicle's nose as... o Point, horizontal axis set as x The axis, perpendicular to the axial direction (i.e., radial direction), is defined as the y-axis, perpendicular to... oxy The plane is set as the starting point of the head tip. z The axis is used to establish a three-dimensional rectangular coordinate system. oxy The plane serves as the primary two-dimensional observation coordinate reference system; (22) according to the diameter of the torpedo underwater vehicle D， linear equations of the head, middle and tail are determined.

3. The method of bionic layout optimization of the dual-torpedo underwater vehicle group according to claim 2, characterized in that, The linear equation of the head is: ； wherein Y represents a radial length, x represents an axial distance of the underwater vehicle in a two-dimensional plane, D represents a diameter of the underwater vehicle, a is a length of the head of the underwater vehicle; The linear equation of the middle part is: ； In the formulae, Y denotes the radial length; The linear equation of the tail is: ； wherein Y denotes the radial length, a, b, c Lh, Lm, and Le are the lengths of the head, mid, and tail sections, respectively, of the underwater vehicle.

4. The method of bionic layout optimization of the dual-torpedo underwater vehicle group according to claim 1, characterized in that, In step (3), the biomimetic shark rib ring-shaped recess structure is a rectangular recess, and the depth of the rectangular recess is... h The thickness is 0.5–1 mm, and the bottom length is [missing information]. L a It is 3~4mm.

5. The method of bionic layout optimization of the dual-torpedo underwater vehicle group according to claim 1, characterized in that, In step (3), the bionic shark rib ring-shaped pit structure is arranged on the surface of the head of the underwater vehicle according to the five equal division points of the head curve.

6. The method of bionic layout optimization of the dual-torpedo underwater vehicle group according to claim 4, characterized in that, In step (3), the distance between the two underwater vehicles in the pair of underwater vehicles L D is 90-120 mm.

7. The method of bionic layout optimization of the dual-torpedo underwater vehicle group according to claim 4, characterized in that, In step (5), when the drag reduction rate does not meet the requirement, the distance between the underwater vehicles L D Adjustment priority is higher than the depth of the bionic shark rib ring concave structure h , the depth of the bionic shark rib ring concave structure h Adjustment priority is higher than the length of the bottom surface L a .

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